Pneumatic power assist apparatus for spot film device

ABSTRACT

A three axis pneumatic power assist system which is particularly adapted to move a spot film device over a patient lying on an Xray table. Three separate pneumatic circuits are adapted to power three mutually perpendicularly movable carriages in response to a control handle mounted on the spot film device so that the spot film device may be easily movable anywhere over the top of the Xray table within predefined limits. A double acting spring biased spool valve is utilized for each of the three axes and is actuable by the control handle to cause a control signal to be fed to a pneumatic actuator which powers the respective carriage. When desirable the control handle and the control valves may be remotely located from the X-ray table and the spot film device with suitable pneumatic interconnection lines being provided therebetween.

United States Patent Koerner et a1.

PNEUMATIC POWER ASSIST APPARATUS FOR SPOT FILM DEVICE Inventors: Harry E. Koerner; William C. Horsey, both of Baltimore, Md.

Assignee: CGR Medical Cheverly, Md.

Filed: Oct. 5, 1971 Appl. No.: 186,660

Corporation,

References Cited UNITED STATES PATENTS Primary Examiner-Walter Stolwein Attorney-J. Brady et al. Rupert [57] ABSTRACT A three axis pneumatic power assist system which is particularly adapted to move a spot film device over a patient lying on an X-ray table. Three separate pneumatic circuits are adapted to power three mutually perpendicularly movable carriages in response to a control handle mounted on the spot film device so that the spot film device may be easily movable anywhere over the top of the X-ray table within predefined limits. A double acting spring biased spool valve is utilized for each of the three axes and is actuable by the control handle to cause a control signal to be fed to a pneumatic actuator which powersthe respective carriage. When desirable the control handle and the control valves may be remotely located from the X-ray table and the spot film device with suitable pneumatic interconnection lines being provided therebetween.

19 Claims, 18 Drawing Figures PATENTED I97? 3. 707 630 SHEET 1 OF 3 PNEUMATIC POWER ASSIST APPARATUS FOR SPOT FILM DEVICE CROSS REFERENCE TO RELATED APPLICATION The subject application is related to co-pending application U.S. Ser. No. 172,631, filed Aug. 18, 1971, entitled Pneumatic Power Assist Apparatus For Spot Film Device," filed in the name of John R. Colston. Said application is also assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to fluid pressure power assist mechanisms and more particularly to a three mutually perpendicular axis pneumatic servo mechanism particularly adapted to control the position of radiological apparatus, e.g., a spot film device.

2. Description of the Prior Art Spot film devices are used in radiological apparatus both for fluoroscopy and radiography and generally include a spot film cassette housing which is mounted for movement on a first carriage called an elevator. The elevator is mounted upon a second carriage called a spot film tower. The elevator is adapted to move up and down in a normally vertical or compression axis on the tower. The tower in turn is mounted upon a third carriage which is adapted to move along a longitudinal axis relative to the X-ray table while the second carriage is adapted to move along a transverse axis. Thus the spot film device is movable in three mutually perpendicular axes relative to the table top so that the spot film apparatus can be moved to any desired position to and from a patient lying on the X-ray table.

Currently in addition to the removable film cassette, the spot film device may also include an X-ray image amplifier, a television camera, or other cameras mounted thereon and the tower may also move the X- ray tube, additional supporting carriages and counterbalance weights. The total weight moved in the longitudinal axis of the table alone could be in the order of 1,000 pounds or more. As a result, the acceleration and frictional forces involved in moving this apparatus have become too great for easy operation of the equipment by radiologists and X-ray technicians and thus some type of power assist becomes desirable.

Power assist systems on X-ray equipment are usually confined to a single axis and are driven by an electric motor. Fluid pressure operated serialographic apparatus is also known in the prior art. However, such apparatus is limited to moving the cassette within the spot film housing by fluid pressure carriage shifting means for selectively controlling the exposure position of the film in the cassette in a plane parallel to the top of the X-ray table. The aforementioned related application, Ser. No. 172,631, filed Aug. 18, 1971 entitled P- neumatic Power Assist Apparatus however does disclose one embodiment of a pneumatic serial mechanism for moving the entire film spot device in any one or more three mutually perpendicular axes simultaneously in order to facilitate bringing the film spot apparatus to a selected position over a patient lying on an X-ray table during the process of making a radiological examination.

SUMMARY Briefly the subject invention is directed to an improved pneumatic power assist system particularly adapted for providing an assisting force function along at least one, but preferably three mutually perpendicular axes of an X-ray spot film device which is moved to a predetermined position and elevation over the top of an X-ray table. A pivoted control arm mounted on the spot film device is selectively coupled to three pneumatic control valves also mounted on the spot film device. Each of the control valves is adapted to respectively control the movement of three carriages which are linearly movable along mutually perpendicular axes relative to the X-ray table top. When desirable the control arm handle and the control valves may be remotely located. Actuation of any of the three control valves by selective movement of the control arm handle along a longitudinal, transverse, or compression axis relative to the X-ray table will actuate the proper control valve which couples an actuation signal to a pneumatic power assist cylinder actuator whose piston is forced to move and translate its movement via a cable and pulley arrangement to a respective carriage to which it is connected. The control arm handle is so configured and located to independently actuate each of the three control valves in response to selective movement in any of the three mutually perpendicular axes.

Each of the three control valves is a double acting spring biased spool valve which is adapted to return to a null position when a force applied by an operator to the control arm handle in the predetermined direction is terminated. Moreover, the control valve includes a valve spool which is chamfered on a portion of its land portions so that a restricted or relatively small bleed air flow is equally provided between two exit ports so that a relatively large spool travel is required to obtain 'a' specific net air flow in either output port as a result of the movement of the spool by the control arm handle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view partiallyin section of a radiological examination table such as an X-ray table which incorporates three mutually perpendicularly movable carriages powered by the embodiments of the subject invention and upon which a spot film device is mounted for movement over the top of the X-ray-table;

FIG. 2 is a side elevational view of the pneumatic actuator employed for providing movement of the spot film device along one (compression) axis of motion;

FIG. 3 is a top plan view partially in section of the pneumatic actuator shown in FIG. 2;

FIG. 4 is a longitudinal cross section of a pneumatic jet pump impedance changer adapted for use in connection with said pneumatic actuator shown in FIG. 2;

FIG. 5 is a perspective view generally illustrative of a control arm handle pivotally mounted on the top of a spot film device for selective actuation of three pneumatic control valves which are adapted to control respective pneumatic pneumatic actuators for three mutually perpendicular axes of desired motion;

FIG. 6 is a front plane view of two bifurcated pivot plates which mount the control handle shown in FIG. 5 on the spot film device;

FIG. 7 is a vertical plan view of the pivot plates illustrated in FIG. 6 and which are shown flexed by means of the control handle along the transverse or Y axis;

FIG. 8 is a top plan view of a spot film device assembly incorporating the preferred embodiment of the subject invention and being illustrative of a portion of the control handle and pneumatic control valves actuated thereby for the Y axis and the longitudinal or X aXIS;

FIG. 9 is a partial end plan view of the assembly shown in FIG. 8, being illustrative of theposition of the control valve for the compression Z axis as well as the control valve for the X axis;

FIG. 10 is a side plan view of the assembly shown in FIGS. 8 and 9, being illustrative of a portion of the control handle and the control valves for the Z and Y axes;

FIG. 11 is a partial perspective view of the mechanical linkage between the control handle and the control valve forthe Y axis;

FIG. 12 is a perspective view of another embodiment of the control handle and the three pneumatic control valves;

FIG. 13 is a top plan view of the preferred embodiment of the pneumatic control valve assembly utilized in connection with the subject invention;

FIG. 14 is a side elevational view of the assembly shown in FIG. 13;

FIG. 15 is a longitudinal cross-sectional view taken along the lines 15-15 of FIG. 13;

FIG. 16 is a cross sectional view of the valve spool and ports shown in FIG. 14 taken along the lines I6-- 16 thereof;

FIG. 17 is a plan view of a valve spool utilized in combination with the control valve assembly illustrated in FIGS. 13 through 16; and

FIG. 18 is a longitudinal cross sectional view partially in section of a second embodiment of a control valve assembly adapted for use in connection with the subject invention.

DESCRIPTION OF THE PREFERRED EM BODIMENTS Referring now to the drawings wherein like numerals refer to like parts throughout, attention is first directed to FIG. 1 wherein reference numeral 20 generally refers to a radiological examination table referred to hereinafter as an X-ray table including a bed 22 and a top 24. The present invention has for its objective the provision of a fluid, preferably pneumatic, power assist means for at least one, but preferably three carriages 26, 28 and 30 which are adapted to move respectively in one of three mutually perpendicular axes for the easy movement of a spotfilm device 32 so that it may be selectively positioned over a patient, not shown, lying on the table top 24. The carriage 26 is adapted to move in a longitudinal or X axis along the bed 22 of thetable 24, being powered by means of a pneumatic actuator 34. The carriage 28 normally referred to as the spot film tower, is slidably mounted on the carriage 26 to move in an axis perpendicular. thereto and extends upwardlyalong one side of the table top 24 in a generally vertical orientation. The lateral carriage 28 or tower is normally adapted to suspend a radiation source, not shown, on the underside of the table top 24 which may be for example an X-ray tube which is located beneath the table top 24. The spot film tower 28 in addition to being able to be moved in the longitudinal or X axis due is adapted for movement thereon in a compression or Z axis which normally constitutes the vertical axis whereby the elevator 30 moves up anddown relative to the table top 24. Movement of the elevator carriage 30 is provided by a third pneumatic actuator 38.

Prior to discussing the pneumatic actuators in detail,

it should be pointed out that the first pneumatic actuator 34 is mounted on the bed 22 of the table 20 and is coupled to the carriage 26 by means of a cable and pulley assembly internally connected to a piston, not shown. The cable assembly connects to the members 40 and 42 shown in FIG. 1. A typical pneumatic actuator is shown in FIG. 2, and will be described in detail subsequently. The second pneumatic actuator 36 for moving the tower 28 is secured to the carriage 26 and has its respective cable and pulley assembly connected to the side of the spot film tower. The third pneumatic actuator 38 for moving the elevator carriage 30 is mounted in a generally upright position at the side of the spot film tower 28, as shown in FIG. 1. Since the three pneumatic actuators 34, 36 and'38 are substantially identical with the exception of actual physical dimension such as length, only one particular assembly need be considered.

Directing attention now to FIG. 2, there is disclosed the pneumatic actuator assembly for moving the elevator 30 up and down along the compression axis on the spot film tower 28. The pneumatic actuator includes a cylinder 44 enclosing a piston 46 and suitable seals which is attached on either side to the cables 48 and 50. These cables in effect constitute a flexible piston rod for connection to the elevator carriage 30. The cable 48extends around apulley 52 and connects to an angle bracket 54 which is secured to the back of the carriage 30. In the same manner the cable 50 extends around the pulley 56 attached to the opposite end of the cylinder 44 and is secured to a second angle bracket 58 which is adjacent the other bracket 54. A top view of this configuration is shown in FIG. 3.

The cable and pulley configuration reduces space and provides a desired mechanical advantage. For table motions requiring less effort for transporting a particus lar carriage, the mechanical advantage derived by a specific embodiment may be used so that the cylinder piston may be made to move one-half or possibly less the traverse of its mating carriage Movement of the piston 46 is caused by the difference in air pressure on each side thereof. To this end the cylinder 44 includes a port at each end thereof for the passage of air either into or out of the cylinder by means of the couplings 60 and 62. Two jet pump impedance changers 64 and 66, one of which is disclosed in FIG. 4, have their outputs respectively connected to the couplings 60 and 62 while their inputs are connected to a respective output port of a pneumatic control valve, notshown. The impedance changers 64 and 66, moreover, have a common pneumatic coupling and silencer means 67 for the passage of air therebetween. Each jet pump impedance changer is comprised of pneumatic fitting 68, which is terminated within the housing 70 in a nozzle 72 (FIG. 4). The nozzle 72 is directed to and is axially aligned with a relatively narrow throat section 74 which is coupled to a second input fitting 76. A diffuser section 78 is placed contiguous with the throat section 74 and terminates in an exit port 142.

In operation, a pneumatic fluid input signal from a control valve, not shown, is coupled to the input fitting 68 whereupon a jet is formed at the nozzle 72 which is directed towards the throat section 74. Additional air is drawn or aspirated from the other fitting 76 which is coupled to the other jet pump impedance changer. The combined air flow through the throat section 74 forms a more uniform velocity distribution as it travels the length thereof and when the air flows through the diffuser section 78, flow velocity decreases but increases the static pressure at the exit port 142 which is coupled to one end of the cylinder 44. It can be seen, therefore, that the application of a pneumatic input signal to one of the jet pump impedance changers will cause an increased pressure to be applied to one side of the piston while pressure on the opposite side thereof is decreased due to the drawing of air therefrom through the other jet pump impedance changer due to the aspiration effect described. A more detailed description of the jet pump impedance changer 66 may be had by reference to the aforementioned related application entitled P- neumatic Power Assist Apparatus For Spot Film Device.

Having thus described the manner in which the three carriages 26, 28 and 30 are moved, attention is now directed to the means for controlling each of the pneumatic actuators 34, 36 and 38 for providing selective power assisted motion of the respective carriages along the longitudinal (X), transverse (Y), or compression (Z) axes for positioning the spot film device 32 over the X-ray table top 24. It should also be pointed out, however, that by a suitable reversal of ports, the carriages 26 and 28 could remain fixed with the table top 24 being moved thereby providing the same relative motion.

I Referring now to FIG. 5, the spot film device 32 generally includes a spot film cassette, not shown, which is adapted to be positioned over an X-ray source secured to the spot film tower 28 and located beneath the table top 24. These devices and their arrangement are not shown because they are well known to those skilled in the art and form no part of the present invention. Also, the spot film device may also include an X- ray image amplifier mounted thereon as well as a television camera or other cameras for the purposes of facilitating a radiological examination. The spot film device, however, does include a fixed hand rest 80 which is adapted to be gripped by an operator for purposes of moving the spot film device to a desired location in absence of the power assist apparatus being operative. The present invention additionally includes a pneumatic power assist control handle 82, referred to hereinafter as the control arm, comprises a relatively long lever arm extending lengthwise over the top surface of the film spot device 32 and being mounted thereon by means of a pair of bifurcated or generally U- shaped flexible metal leaf members 84 and 86 which are adapted to act as pivots. One end portion 88 of the control arm 82 is fabricated so as to be co-extensive with the hand grip so that manipulation of the handle can be accomplished while the operators hand rests on the hand grip 80. It should also be appreciated, however, that when desirable the entire end portion 88 may be gripped in the hand of the operator.

Considering now the flexible pivot configuration including the U-shaped members 84 and 86, reference is now made briefly to FIGS. 6 and 7 in combination with FIG. 5. The members 84 and 86 have one end thereof respectively connected to vertical posts 90 and 92 which are attached to the spot film device 32. The opposite end of the members 84 and 86 are connected to projections 94 and 96 located intermediate the ends of and which form a portion of the control arm 82. On the opposite side of the end portions of the U-shaped members 84 and 86 are located four rigid pad members 98, 100, 102 and 104 which substantially match the configuration of the posts 90 and 92 as well as the control arm projections 94 and 96. The purpose of the pads 98, 100, 102 and 104 is to insure equalization of deflection of the members 84 and 86 in accordance with a force applied to the end portion 88 of the control arm 82 in either of three mutually perpendicular X, Y and Z axes. Since the U-shaped members 84 and 86 are comprised of relatively thin material and are co-planar, operator force applied to the control arm 82 along one axis only will cause the members 84 and 86 to deflect in that axis only with no deflection in the other two mutually perpendicular axes. For example, by reference to FIG. 7, it can be seen that a force applied along the transverse or Y axis causes the upper portions of both members 84 and 86 to be translated by an equal amount in the Y direction while the lower portions remain fixed due to their attachment to the posts 90 and 92. Movement of the arm 82 along the longitudinal or X axis would cause the members 84 and 86 to buckle or deflect in opposite directions. A force applied along the Z axis would cause a torsion of both members 84 and 86.

Since the control arm 82 is connected to the pivots intermediate its ends, it can be seen by reference to FIG. 5, that any motion applied to the end 88 of the control arm 82 will be translated to the opposite end portion of the control arm 82 by the operation of the bifurcate members 84 and 86. Accordingly, three pneumatic control valves 106, 108 and 110 are selectively mounted on the rear portion of the spot film device 32 and are mechanically coupled to the control arm 82 so as to be respectively actuated for the three axes of desired motion as signalled by operation of the operator by movement of the end portion 88 of the control arm 82.

Referring now to FIGS. 8 through 11 wherein structural details of the configuration shown generally in FIG. 5 is presented, the control arm 82 is comprised partially of two linearly offset arm members 112. and 114 with a counter balance weight member 116 secured to the end thereof. The counter balance weight 116 has for its purpose the perfect balancing of the control handle 82 irrespective of table attitude. A pneumatic control valve 108 for the X axis of motion is coupled by means of resilient actuator means such as a wire 118 to the member 114 through a mechanical linkage which is shown in greater detail in FIG. 11. The wire 118 couples to a valve spool which is slidably mounted in the valve body. The linkage comprises a vertically depending metal plate 120 which is secured V to the outer side of the member 1 14. The plate .120 includes a hole 122 through which a rod 124 is slidably inserted therethrough and retained. The rod 124 is rigidly connected to an elongated rectangular block 126 to which the wire actuator 1 18 is attached by suitable hardware as shown. A flexible leaf spring member 128 is attached to the end of the block 126. The other end of the leaf spring 128 is coupled to an angle bracket 130 which is mounted at its other end on the upper surface of the spot film device 32. Additionally, rigid pads 132 and 134 are mounted to the opposite side of the leaf spring member 128 where it attaches to the block 126 and the angle bracket 130 for insuring proper deflection to the X axis direction. Movement of the control arm 82 along the X axis will cause the leaf spring member 128 to flex with the rod 124 slidably retained in the hole 122 acting as a pivot. The position of the actuator wire 118 causes valve 108 to be operated for any movement of the control arm 82 along the Y axis; however, it should be observed .that there is not a one to one distance of movement ratio of the arm 82 to wire 1 18 due to the offset position of the wire 118 in relation to the contact point provided by the rod 124 and the hole 122. The closer the wire 118 is axially aligned with the member 114, the closer the one to one ratio becomes.

lnsofaras the actuator travel of the control valves 106 and 110 for the X and Z axes respectively is concerned, there is a one to one relationship of the movement of the control arm 82 to the appropriate valve. Considering first the control valve for the X axis, it comprises an actuator wire 136 coupled to a valve spool and is attached to an angle bracket 138 which depends downwardly from the end portion 140 of the control handle member 114 and is adjacent to the counter balance weight 116. It can be seen from FIGS. 8 and 9 that any movement of the control arm 82 along the X axis at the junction point of the control handle and wire 136 will effect a direct one to one movement of the actuator wire 136. FIG. 9 additionally shows the wire actuator 140 for the control valve 110 being connected to the rear surface of the counter weight 116 such that any vertical movement of the control arm and counter weight 116 along the Z axis effects a direct movement of the actuator wire 140.

Where there exists a need for a less sensitive and/or reduced degree of travel of the actuator wires relative to the travel of the control arm 82 for actuation of the control valves, a configuration such as shown in FIG. 12 may be resorted to. In this configuration the control arm 82 includes a right angle extension arm member 142 at the rear extremity thereof which contains a hole 144 wherein an extension rod 146 is adapted to slidably fit therein. The rod 146 is attached to a mounting block 148 which is secured to the upper surface of the spot film device 32 adjacent the pivot members 84 and 86. The rod 146 is pivotally mounted to the projection 150 which is located on one side of the mounting block 148. An actuating bar 152 is pivotally mounted between a pivot point 154 on the top surface of the mounting block 148 and a pivot point 156 located on the upper surface of the control arm 82 adjacent the bifurcated pivot members 86 and 84. It is significant to note that the pivot points 154 and 156 as well as the projection 150 are co-planar in the X-Z plane. Moreover by locating the pivot points 154 and 156 substantially in the plane of the control arm pivot members'84 and 86 the connection of the actuator wire 118 to the lever arm 152 intermediate the pivot points 154 and156 feels only Y axis motion. The position of the connection of the actuator wire 118 along the lever arm determines the ratio of movement between the control arm 82 in the Y direction to the movement of the actuator wire 1 18 in the same direction. Due to the sliding contact of the rod 146 in the hole 144, movement of the control arm 82 in the Y direction has no effect on the rod. However, movement in the 'Z and X direction will cause movement of the rod 146 and actuator wires and 136 respectively. The wires 140 and 136 are coupled to the rod 146 by means of a sliding link 158. The position of the connection link 158 along the rod 146 between the hole 144 and the projection determines the ratio of movement of the control arm to the respective actuator wires. Thus selective sensitivity of each of the control valves 106, 108 and 110 for the X, Y, and Z directions can be balanced or unbalanced as desired.

Each of the pneumatic control valves 106, 108 and 110 are identical in construction and their associated components are disclosed in FIGS. 13 through 17.'The structure of the three control valves comprises a chamfered spool valve assembly including double acting spring bias means for returning the valve spool to a predetermined center or null" position whenever the wire actuator axially connected to the spool valve is moved by means of the control arm 82 and then released. The assembly shown in FIGS. 13 through 17 includes a valve body 160 which is rigidly mounted on the spot film device as shown in FIGS. 8 through 10. The housing includes an input port 162 and two output ports 164 and 166 coupled to a valve chamber 167. These ports arecoupled to the respective air lines, not shown, by means of the pneumatic channels 168, 170 and 172 in the valve body. A valve spool 174 is slidably mounted in the valve chamber 167 and is adapted to selectively interconnect the output ports 164 and 166 with the input port 162 depending upon its position. The valve spool 174 is comprised of two relatively larger diameter cylindrical end sections 178 and 180, referred to as lands, which are separated by a smaller diameter cylindrical section 182 which forms an annular valving area in combination with the chamber 167 shown in FIG. 16.

The valve spool 174 is unique in that the lands 178 and are modified by having opposing chamfered surfaces 184 and 186 which are machined or otherwise fabricated into a portion of the cylindrical land surface adjacent the intermediate annular section 182. When the valve spool 174 is centered in the chamber 176, the chamfered surfaces 184 and 186 being of identical configuration, provide a balanced bleed air flow to both exit ports 164 and 166 from the input port 162. It should be noted, however, that the bleed air flow only occurs at the location of the chamfered surfaces 184 and 186. This is in complete contrast to presently known state of the art spool valves wherein air bleed takes place around the complete circumference of the lands forming the valve spool. The effect of the spool valve configuration shown in FIGS. 16 and 17 is to reduce the sensitivity of the valve in order to obtain a null" position with little effort by manual setting of the spool position, otherwise relatively small spool travel would effect a net air flow which is greater than is desirable and difficult to control.

In the present invention the valve body 160 is mounted on or rigidly secured to the spot film device 32; however, when desirable, the valve body 160 may be mounted on an angle bracket, not shown, which is secured to the spot film device 32. In either case the valve body is fixed with valve spool being movable. Centering of the valve spool 174 to a null position is obtained by means of a bracket member 188 located on top of the valve body 160 in combination with a double acting compression spring 190 as shown in FIGS. 13, 14 and 15. The bracket member 188 includes a channel section 192 (FIG. 13), an upper section 194 including an elongated slot 196 which runs parallel to valve spool travel, and an angle end portion 198 through which a valve body positioning screw 200 is threaded. The channel section 192 is comprised of a pair of opposing side members 202 and 204 which are separated by a predetermined distance so as to maintain the spring 190 under compression at all times. Moreover the spring 190 is preferably selected so that its compression characteristic matches the desirable force exerted on the arm 82 by the operator. A pair of plastic discs 206 and 208 are interposed between the spring 190 and respectively abut the side members 202 and 204 and include raised portions which oppose one another for axially aligning the spring 190 with the valve spool actuating wire 118 which passes therethrough. The side members 202 and 204 additionally include respective circular openings 210 and 212 which are of relatively smaller diameter than the respective adjacent discs 206 and 208. A pair of metal sleeves 214 and 216 are fitted on the actuator wire I18 and are adapted to be clamped thereto by means of set screws 218 and 220. With the sleeves 214 and 216 positioned adjacent the respective disc 206 and 208 as shown in FIGS. 13 and 14, travel of the actuator wire in either direction will cause one of the discs 206 and 208 to be moved by the respective sleeve to further compress the spring 190. A release of the force applied to the wire 118 will cause the spring 190 to reposition the discs 206 and 208 against the sides 202 and 204 thereby urging the sleeves 214 and 216 and wire 118 to a predetermined null position.

At assembly the sleeves 214 and 216 are adjusted and locked to contact the discs 206 and 208 While applying no additional stress to the spring 190. Screws 222 and 224 (FIG. 13) are run into the valve body 160 through the slot 196 which as noted earlier is oriented in the same direction as the axis of the valve spool 174, With the locking screws 222 and 224 snug but not tight the bracket 188 is roughly positioned to provide substantially equal air output from the two output ports 164 and 166 when a pneumatic source is coupled to the input port 162. With the roughfadjustment thus made, the set screw 200 in the end portion 198 is manipulated forcing movement of the valve body 160 by its contact therewith until a fine adjustment of the rate of flow through both exit ports 164 and 166 is exactly equal. At that point the locking screws 222 and 224 are tightened.

With the configuration thus described, the valve spool 174 is maintained at the null position of the valve due to the force exerted by the compression spring 190. Any tendency to actuate the valve is restrained by this force. When an external force is applied to the actuator wire 118 through the control arm 82, the spool is moved off center and a pneumatic output signal will be provided at one of the output ports 164 or 166, depending upon the direction in which the spool is moved. When the external force applied to control arm 82 is released, the valve spool 174 is forced back to the center or null position by action of the spring 190.

A second embodiment of the control valve assembly is shown in FIG. 18 wherein the valve spool 174 is kept stationary while the valve body 160 is moved in accordance with a force applied thereto from the control arm 82 such as shown in FIG. 12. In this configuration, the actuator wire 118 is clamped to a rigid pedestal 226 which is in turn secured to or a part of the spot film device 32. The valve body 160 is fixed to an angle bracket 228 which has its lower extremity coupled to the base of the pedestal 226 by means of a relatively thin leaf spring 230. Also secured to the angle bracket 228 is a dash pot or damper 232 which has its plunger 234 mechanically coupled back to an arm 236 which connects to the control arm 82, not shown, mounted on the spot film device. The arm 236, moreover, is adapted to pass through the pedestal 226 and the angle bracket 228 and terminates in a spring wire 238 which is secured to another angle bracket member 240. The base or lower portion of the angle bracket 240 is coupled to the base of the angle bracket 228 by means of a second thin leaf spring 242 so that it is coplanar with leaf spring 230. Any movement of the arm 236 is coupled to the angle bracket 240 by the spring wire 238. This movement is coupled to the angle bracket 228 through the leaf spring 242. The action of the leaf spring 242 in combination with the leaf spring 230 causes the valve body 160 to tilt in one direction or another thereby effecting relative movement of the valve chamber 176 with the valve spool 174. The purpose of the dash pot 232 is to provide a damping means for the assembly. The dash pot 232 additionally includes a control knob 244 for controlling the amount of venting through an orifice, not shown. The piston 234 is operated close to the end of the stroke in order to achieve minimal air compressibility effect for desired operation.

Having thus described the mechanical details of the elements comprising the subject invention, its operation will briefly be considered. Whenever movement of the spot film device 32 is desired, the operator moves the end portion 88 of the control arm 82 in the direction in which movement of the spot film device is desiredv This movement is coupled as a force to one or more of the control valves I06, 108 and 110 whose respective spool valve 174 is moved away from its spring biased null position. When this occurs, a pneumatic control signal is coupled from the respective input port 162 to one of the output ports 164 or 166 which is then fed by means of its respective pneumatic channel 170 and 172 and appropriate air feed lines to the input of one of the jet pump impedance changers 66and 68. Depending upon which impedance changer 66 or 68 receivesthe pneumatic input signal at the respective input fitting 68, an output pressure signal will be fed to one side of the piston 46 which will move the piston towards one'end of the cylinder. This movement of the piston 46 will then be transferred to the flexible piston rod i.e.,'the cable and pulley assembly which in turn will move the carriage to which it is attached. It may also be desirable to use pressure regulators, not shown, in the feed lines to balance the power exerted by thethree actuators due to the difference in masses moved in the three axes. .When the force ap-' plied to the control arm 82 is released, the respective compression spring 190 will force its spool valve 174 back to its null position by means of the action of the spring 190 on the discs 206and 208 as well as the sleeves 214 and 216 locked to the actuator wire 118 and motion of the respective carriage will stop at that location, remaining there until the control handle 82 is again iactivated by the operator.

It should be pointed out that the terms and expressions which have been employed herein are used as terms of description only and not of limitation. Also, there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. For example, a fixed X-ray beam table may readily be adapted wherein the transverse and/or longitudinal axis carriages are fixed and the table made movable relative thereto. It is to be recognized therefore that various other modifications are possible within the scope of the invention as claimed.

We claim as our invention:

1. A manually operated fluid power assist system for radiological or similar apparatus comprising, in combination: 1

a base member and at least one carriage supported by said base member and wherein said at least one carriage supports said radiological or similar apparatus; I

pivotally mounted control arm means;

a fluid control valve including valving means, slidably mounted in a valve body, an input port and two output ports and bias means coupled to said valving means for maintaining the valving means in a normally centered null position between said input portand said two output ports whereby substantially equal outputs from said output ports are provided when said control arm means is in a first position;

means coupling said control arm means to said valving means and providing actuation thereof in accordance with a force applied to said control arm means during a second position of said control arm means, said second position being along at least one linear axis of three mutually perpendicular axes of desired movement of said radiological apparatus wherein actuation of said valve provides a fluid output signal from one of said output ports; and

a fluid actuator including a cylinder and piston intercoupling said at least one carriage and said base member and having two input ports respectively coupled to said two output ports of said control valve, relative motion between said base member and said at least one carriage being provided in a predetermined linear direction along said one axis in accordance with said fluid output signal applied thereto from one of said output ports as a result of operating said control arm means. I

2. The invention as defined by claim 1 wherein said fluid actuator comprises 'a cylinder including ports at each end thereof,- a piston freely movable inside of said cylinder between said ports and a first and a second flexible cable attached to opposite sides of said piston and additionally including pulley means coupling said flexible cables to said carriage whereby movement of said piston is translated to said carriage.

3. The invention as defined by claim 1 wherein said base member comprises a radiological examination table. v

4. The invention as defined by claim 3 wherein said carriage is movable and located with respect to said table so as to move along a longitudinal axis with respect to the top of said examination table.

5. The invention as defined by claim 4 and additionally including: 7

a second movable carriage mounted on said movable carriage recited above and being adapted to move' in a transverse axis relative to the top of said examination table;

a third movable carriage mounted on said second movable carriage and adapted to move in a compression axis relative to the top of said examination table;

a second and a third fluid control valve being coupled to said control arm means and being actuated thereby for movement of said control arm means respectively along said transverse and compression axes;

a second and a third fluid actuator respectively coupled to said second and third control valve, each actuator additionally being respectively coupled to said second and third movable carriage for providing translation thereof in accordance with an output signal applied thereto from said second and third control valve for providing a system providing a power assist along said three mutually perpendicular axes of motion relative to the top of said examination table.

6. The invention as defined by claim 1 wherein said radiological apparatus comprises a spot film device, said base member comprises a spot film tower and said at least one carriage comprises an elevator carriage which supports said spot film device,

7. The invention as defined by claim 1 wherein said control arm means is mounted on said radiological or similar apparatus and additionally including a pair of bifurcated flexible members respectively connected at one end thereof to said apparatus and at the other end to said control arm means intermediate its ends.

8. The invention as defined by claim 7 wherein said control arm means comprises an'elongated member including means at one end thereof for -providing manipulation thereof by an operator.

9. The invention as defined by claim 8 wherein said elongated member is mounted on the top surface of said apparatus and generally running lengthwise therewith and additionally including a counter balance weight attached to the other end thereof.

10. The invention as defined by claim 9 and additionally including pads located at the ends of said bifurcated flexible members for equalizing deflection of said members in either direction of movement.

11. The invention as defined by claim wherein said control arm means includes an arm pivotally attached to said radiological or similar apparatus, a pair of coplanar flexible bifurcated members coupling said control arm means to said apparatus, said arm being disposed generally along said transverse axis of motion, and including means for manipulating said arm at one end thereof and a second arm portion running along the longitudinal axis located at the other end of said arm and having a sliding contact joint therein, a rigid member secured to said sliding contact joint and being substantially co-planar and parallel with said control arm means and additionally including a selectively movable coupling means slidably mounted thereon for coupling to selected control valves actuable by control arm means motion along said longitudinal and compressionable axis, and a pivot bar member located substantially in the plane of said bifurcated members and being pivotally attached to said control arm means and including means for being coupled to a selected control valve actuable in response to movement along said transverse axis.

127 The invention as defined by claim 1 wherein said valving means comprises a valve spool including first and second cylindrical land portions separated by a generally cylindrical intermediate portion of reduced diameter and providing an annular valving area thereby, each said land portions additionally including a chamfered surface adjacent said intermediate portion for providing a relatively small fluid bleed region from said input port to both said output ports at the location of said chamfered surfaces.

13. The invention as defined by claim 12 wherein said chamfered surfaces directly oppose one another.

14. The invention as defined by claim 12 wherein said coupling means to said control arm means comprises a resilient member attached to said valve spool and wherein said means for maintaining the valve spool in a normally centered null position comprises double acting spring bias means.

15. The invention as defined by claim 14 wherein said resilient means comprises a wire actuator, and:

said double acting spring bias means comprises:

a. a bracket attached to said valve body, being movable along an axis parallel to the axial movement of said valve spool, said bracket additionally including a channel portion comprised of two generally parallel opposing members separated by a predetermined distance;

b. a first and a second freely movable spring retaining means slidably mounted on said spring actuator wire and respectfully positioned on the inner faces of said first and second member and being adapted to abut said faces when urged thereagainst by a spring member;

c. a compression spring member located between said first and second retainer means and being generally axially aligned with said spool valve and said wire actuator; and a first and a second sleeve member selectively fastened to said wire actuator respectively on the opposite side of said first and said second spring retaining means such that by selective movement of said wire actuator in an axial direction causes one of said spring retaining means to be urged towards the other spring retaining means to further compress said compression spring means, said spring means then tending to return said spool valve to its null position when the force applied to the spring actuator causing its movement is removed.

16. The invention as defined by claim 1 wherein said control valve comprises a double acting spring biased spool valve including spring bias means, a resilient actuator arm coupled to said valve spool and means coupled to said actuator arm for positioning said spool valve to said null position under the influence of said spring bias means.

17. The invention as defined by claim 16 wherein said valve spool is comprised of a first and a second cylindrical land portion separated by an intermediate valving portion, and wherein said land portions include a chamfered surface on a portion of said land adjacent said valving portion.

18. The invention as defined by claim 12 wherein said coupling means to said control arm means comprises a resilient actuator arm connected to said valve spool, and additionally including:

a. a first rigid member, having an opening therethrough, secured to said radiological apparatus and including means attaching said resilient actuator thereto;

b. a second rigid member having at least one opening therein and including means for mounting said valve body thereon;

c. a first fiat spring member connecting said second rigid member to said first rigid member;

. a pneumatic damper including a cylinder and a plunger including means for attaching said cylinder to said second rigid member; e. a third rigid member; and f. a second flat spring interconnecting said third rigid member to said second rigid member and being substantially co-planar with said first fiat spring; an actuator member connected to said control arm means, being coupled to said plunger and passing through said openings in said first and second rigid member and terminating in a resilient connection to said third rigid member, whereby movement of said actuator is coupled as a bending moment to said third rigid member which is transferred to said second rigid member and said first flat spring member which causes said valve body to move in accordance therewith to provide an output signal from one of said output ports while said valve spool remains stationary.

19. The invention as defined by claim 18 wherein said damper additionally includes adjustable venting means for selectively varying the pneumatic compressability effect of said damper. 

1. A manually operated fluid power assist system for radiological or similar apparatus comprising, in combination: a base member and at least one carriage supported by said base member and wherein said at least one carriage supports said radiological or similar apparatus; pivotally mounted control arm means; a fluid control valve including valving means, slidably mounted in a valve body, an input port and two output ports and bias means coupled to said valving means for maintaining the valving means in a normally centered null position between said input port and said two output ports whereby substantially equal outputs from said output ports are provided when said control arm means is in a first position; means coupling said control arm means to said valving means and providing actuation thereof in accordance with a force applied to said control arm means during a second position of said control arm means, said second position being along at least one linear axis of three mutually perpendicular axes of desired movement of said radiological apparatus wherein actuation of said valve provides a fluid output signal from one of said output ports; and a fluid actuator including a cylinder and piston intercoupling said at least one carriage and said base member and having two input ports respectively coupled to said two output ports of said control valve, relative motion between said base member and said at least one carriage being provided in a predetermined linear direction along said one axis in accordance with said fluid output signal applied thereto from one of said output ports as a result of operating said control arm means.
 2. The invention as defined by claim 1 wherein said fluid actuator comprises a cylinder including ports at each end thereof, a piston freely movable inside of said cylinder between said ports and a first and a second flexible cable attached to opposite sides of said piston and additionally including pulley means coupling said flexible cables to said carriage whereby movement of said piston is translated to said carriage.
 3. The invention as defined by claim 1 wherein said base member comprises a radiological examination table.
 4. The invention as defined by claim 3 wherein said carriage is movable and located with respect to said table so as to move along a longitudinal axis with respect to the top of said examination table.
 5. The invention as defined by claim 4 and additionally including: a second movable carriage mounted on said movable carriage recited above and being adapted to move in a transverse axis relative to the top of said examination table; a third movable carriage mounted on said second movable carriage and adapted to move in a compression axis relative to the top of said examination table; a second and a third fluid control valve being coupled to said control arm means and being actuated thereby for movement of said control arm means respectively along said transverse and compression axes; a second and a third fluid actuator respectively coupled to said second and third control valve, each actuator additionally being respectively coupled to said second and third movable carriage for providing translation thereof in accordance with an output signal applied thereto from said second and third control valve for providing a system providing a power assist along said three mutually perpendicular axes of motion relative to the top of said examination table.
 6. The invention as defined by claim 1 wherein said radiological apparatus comprises a spot film device, said base member comprises a spot film tower and said at least one carriage comprises an elevator carriage which supports said spot film device.
 7. The invention as defined by claim 1 wherein said control arm means is mounted on said radiological or similar apparatus and additionally including a pair of bifurcated flexible members respectively connected at one end thereof to said apparatus and at the other end to said control arm means intermediate its ends.
 8. The invention as defined by claim 7 wherein said control arm means comprises an elongated member including means at one end thereof for providing manipulation thereof by an operator.
 9. The invention as defined by claim 8 wherein said elongated member is mounted on the top surface of said apparatus and generally running lengthwise therewith and additionally including a counter balance weight attached to the other end thereof.
 10. The invention as defined by claim 9 and additionally including pads located at the ends of said bifurcated flexible members for equalizing deflection of said members in either direction of movement.
 11. The invention as defined by claim 5 wherein said control arm means includes an arm pivotally attached to said radiological or similar apparatus, a pair of co-planar flexible bifurcated members coupling said control arm means to said apparatus, said arm being disposed generally along said transverse axis of motion, and including means for manipulating said arm at one end thereof and a second arm portion running along the longitudinal axis located at the other end of said arm and having a sliding contact joint therein, a rigid member secured to said sliding contact joint and being substantially co-planar and parallel with said control arm means and additionally including a selectively movable coupling means slidably mounted thereon for coupling to selected control valves actuable by control arm means motion along said longitudinal and compressionable axis, and a pivot bar member located substantially in the plane of said bifurcated members and being pivotally attached to said control arm means and including means for being coupled to a selected control valve actuable in response to movement along said transverse axis.
 12. The invention as defined by claim 1 wherein said valving means comprises a valve spool including first and second cylindrical land portions separated by a generally cylindrical intermediate portion of reduced diameter and providing an annular valving area thereby, each said land portions additionally including a chamfered surface adjacent said intermediate portion for providing a relatively small fluid bleed region from said input port to both said output ports at the location of said chamfered surfaces.
 13. The invention as defined by claim 12 wherein said chamfered surfaces directly oppose one another.
 14. The invention as defined by claim 12 wherein said coupling means to said control arm means comprises a resilient member attached to said valve spool and wherein said means for maintaining the valve spool in a normally centered null position comprises double acting spring bias means.
 15. The invention as defined by claim 14 wherein said resilient means comprises a wire actuator, and: said double acting spring bias means comprises: a. a bracket attached to said valve body, being movable along an axis parallel to the axial movement of said valve spool, said bracket additionally including a channel portion comprised of two generally parallel opposing members separated by a predetermined distance; b. a first and a second freely movable spring retaining means slidably mounted on said spring actuator wire and respectfully positioned on the inner faces of said first and second member and being adapted to abut said faces when urged thereagainst by a spring member; c. a compression spring member located between said first and second retainer means and being generally axially aligned with said spool valve and said wire actuator; and d. a first and a second sleeve member selectively fastened to said wire actuator respectively on the opposite side of said first and said second spring retaining means such that by selective movement of said wire actuator in an axial direction causes one of said spring retaining means to be urged towards the other spring retaining means to further compress said compression spring means, said spring means then tending to return said spool valve to its null position when the force applied to the spring actuator causing its movement is removed.
 16. The invention as defined by claim 1 wherein said control valve comprises a double acting spring biased spool valve including spring bias means, a resilient actuator arm coupled to said valve spool and means coupled to said actuator arm for positioning said spool valve to said null position under the influence of said spring bias means.
 17. The invention as defined by claim 16 wherein said valve spool is comprised of a first and a second cylindrical land portion separated by an intermediate valving portion, and wherein said land portions include a chamfered surface on a portion of said land adjacent said valving portion.
 18. The invention as defined by claim 12 wherein said coupling means to said control arm means comprises a resilient actuator arm connected to said valve spool, and additionally including: a. a first rigid member, having an opening therethrough, secured to said radiological apparatus and including means attaching said resilient actuator thereto; b. a second rigid member having at least one opening therein and including means for mounting said valve body thereon; c. a first flat spring member connecting said second rigid member to said first rigid member; d. a pneumatic damper including a cylinder and a plunger including means for attaching said cylinder to said second rigid member; e. a third rigid member; and f. a second flat spring interconnecting said third rigid member to said second rigid member and being substantially co-planar with said first flat spring; g. an actuator member connected to said control arm means, being coupled to said plunger and passing through said openings in said first and second rigid member and terminating in a resilient connection to said third rigid member, whereby movement of said actuator is coupled as a bending moment to said third rigid member which is transferred to said second rigid member and said first flat spring member which causes said valve body to move in accordance therewith to provide an output signal from one of said output ports while said valve spool remains stationary.
 19. The invention as defined by claim 18 wherein said damper additionally includes adjustable venting means for selectively varying the pneumatic compressability effect of said damper. 